From main 3r FAQ
When is a monster character considered epic level? Do
you “go epic” when your total class levels equal 20 or when
your total Hit Dice equal 20? Is a monster character eligible
for epic-level feats (such as Epic Toughness) when its
character level is 21+ or when its ECL is 21+?
A monster becomes an epic-level character when its
character level hits 21, just like any other character. A
monster’s character level equals its racial Hit Dice + class
levels. (See the second sidebar on page 25 of the Epic Level
Handbook.)
A creature’s ECL has no effect on when it becomes an epic
character, although once it becomes an epic character, its ECL
continues to affect how much experience it earns and when it
can add a new level.
的确,神经巫师会的不同来源资料又矛盾了……根据core rule>faq的原则,我同意erwin老爷的观点,嗯嗯